Droplet actuators are used to conduct a wide variety of droplet operations. A droplet actuator typically includes two plates separated by a space. The plates include electrodes for conducting droplet operations. The space is typically filled with a filler fluid that is immiscible with the fluid that is to be manipulated on the droplet microactuator. Surfaces exposed to the space are typically hydrophobic. There is a need in the art for immunoassays to be performed in a droplet actuator. The immunoassays may include magnetic beads. Further, there is a need for improved methods of effectively washing magnetic beads for use in magnetic immunoassays.